Nutritional support for cancer patients has been studied extensively. It provided a substantial improvement in nutritional status of cancer patients whose malnutrition was due to reduced oral intake, but it fell short of its goals when the malnutrition was due to malignancy. No improvement in the tumor's response to therapy has been demonstrated by this approach, which primarily manipulated protein and caloric intake in a generic strategy.
In the past three decades, studies have repeatedly shown that some foods contain components with antitumor or immune-enhancing activities. These components are nontoxic and have different modes of action, and their individual antitumor activities are modest. A partial list of these components is presented in Table 1. The use of fruits and vegetables, which were not specifically selected for their antitumor attributes and may contain only a few of these components, for cancer prevention has been recommended by the American Cancer Society and the National Cancer Institute; their increased consumption is considered a major cause for the reduction in cancer-related deaths in recent years.
TABLE 1Non-toxic Antitumor Components in Plants1Antitumor ComponentsFunctionsProtease inhibitors in soybeanSuppress chemically induced carcinogenesis incolon, anal gland, oral cavity, lung, breast, and skinAutoclave-resistant factor inProtection against metastasis of radiation-inducedsoybeanthymic lymphosarcoma and weight lossPlant sterolsProtective effect against tumorigenesis in colonicmucosaSaponin (found in soybeans)Potentiation of rabies vaccine in miceAntitumor activityInhibition of induction of Epstein-Barr virusGenistein (found in soybeans)Inhibits angiogenesis and growth of human prostatecancerBiochanin A (found in soybeans &Inhibits human prostate cancermung beans)Other isoflavonesInhibit growth of human cancer cell lines derivedfrom gastrointestinal tractInositol hexaphosphate (found inEnhances NK cell activity and suppresses tumorsoybeans or mung bean)growthSuppresses tumor formation and growthInhibits growth of human leukemia cells andinduces differentiation of K-562 cellsβ-Glucans (e.g., lentinan) (found inHost-dependent inhibition of sarcoma 180 cellmushrooms)growthImmunoaccelerators, immunopotentiators, andimmunomodulatorsEnhance production of IL-1, TNF, LAK activity,cytotoxic T lymphocytes, cytotoxic peritonealexudate cellsLectins (found in mung beans)Selective stimulation of T lymphocyte proliferation1Abbreviations are as follows:NK, natural killer;IL-1, interleukin-1;TNF, tumor necrosis factor;LAK, lymphokime-activated killer.
Non-small cell lung cancer (NSCLC) causes the death of >400,000 patients annually in the United States and Europe. The benefit of conventional therapies for unresectable stage IIIB and IV NSCLC patients is marginal; the generally accepted median survival time (MST) of stage IV patients has remained 4-6 months for the control group and 6-10 months for the treatment group, and the one-year survival time is usually only 20%. Even stage I NSCLC patients have a 52% death rate due to lung cancer within two years when treated with radiotherapy alone. Clearly, more effective therapies are needed.
With regard to AIDS patients, improvement in CD4+ cell count has become a major area of research in AIDS therapies. Current therapies can not increase CD4+ counts to normal range in the 12-month treatment period. Many patients are still dying from depressed immune functions even when their serum HIV load can be reduced to an undetectable level by antiretroviral therapy.
Continuous treatment with toxic antiretroviral drugs for a long period of time has generated instances of intolerable toxicity; many patients cannot continue these highly toxic treatments. Therefore, it would be useful to the industry to provide non-toxic treatments that are effective against malignancies and viral infections.